Various resin compositions that exhibit an excellent heat resistance and excellent electrical properties have been developed and proposed as electronic devices and components that employ such resin compositions. For example, Patent Document 1 and Non-patent Documents 1 and 2 provide baked resin products, for example, films, obtained by baking a resin composition such as the film of a benzoxazine structure-containing precursor.
Patent Document 1 discloses the structure of a main chain-type aromatic benzoxazine constituted from bisphenol, an aromatic diamine, and formaldehyde; a resin composition comprising a BisA-BAPP-derived main chain-type aromatic benzoxazine; and the fact that the baking temperature for baking this composition is 180° C.
Non-patent Document 1 also discloses films obtained by heating each of the following to 240° C.: a precursor film comprising a main chain-type aromatic benzoxazine originating from methanedianiline (MDA), and a precursor film comprising a main chain-type aliphatic benzoxazine originating from hexamethylenediamine (HDA).
In addition, Non-patent Document 2 describes the governing temperature for the ring-opening polymerization of main chain-type benzoxazine and teaches that benzoxazine undergoes a complete ring-opening polymerization when curing is carried out by ring opening of the oxazine ring at the exothermic peak temperature from the exothermic peak in the DSC chart.
However, while the existing baked resin products do have fairly good electrical properties, at present their heat resistance has yet to reach acceptable levels. Moreover, there is also desire for improvements in the properties of electronic devices and components that employ baked resin products as insulating materials.    Patent document 1: Japanese Patent Application Laid-open No. 2003-64180    Non-patent document 1: Takuya KANO, Tarek AGAG, and Tsutomu TAKEICHI, Synthesis and Ring-opening Polymerization of Symmetric High Molecular Weight Polybenzoxazine Precursors, Polymer Preprints, Japan, Volume 54, No. 1 (2005), p. 1818.    Non-patent document 2: Kazuya IIO, Tarek AGAG, and Tsutomu TAKEICHI, Synthesis and Ring-opening Polymerization of Asymmetric High Molecular Weight Polybenzoxazine Precursors, Polymer Preprints, Japan, Volume 54, No. 1 (2005), pp. 1818-1819.
An object of the present invention is therefore to provide a baked resin product that exhibits an excellent heat resistance.
An other object of the present invention is to provide an electronic device that incorporates this baked resin product.